1. Field of the Invention
The present invention relates to an optical fiber component for Raman amplification, for Raman amplification of signal light of a plurality of channels having mutually different wavelengths, a Raman amplifier including the same and an optical communications system including the Raman amplifier.
2. Related Background Art
In an optical communications system in which communication is performed using signal light, the optical power of the signal light that is emitted from the transmitter is small when it arrives at the receiver, due to transmission loss while the signal light propagates along the optical transmission line. When optical power of the signal light reaching the receiver is below the predetermined value, reception errors are generated, with the result that normal optical communication cannot be performed. Accordingly, compensation of the transmission loss of the signal light in the optical transmission line is effected by providing an optical amplifier between the transmitter and receiver and amplifying the signal light by means of the optical amplifier.
Also, in a wavelength division multiplexing (WDM) optical communications system in which signal light of a plurality of channels having mutually different wavelengths are transmitted in multiplexed fashion, it is important to flatten the gain spectrum in the amplification wavelength band of the optical amplifier. The reason for this is that when the gain spectrum is not flat in the amplification wavelength band, there is a possibility that cases where reception is performed normally at the receiver for each signal channel and cases where reception errors occur may arise. In the case of a Raman amplifier, such flattening of the gain spectrum is achieved by suitably setting the respective amounts of power of the pumping light of the various channels that are supplied to the optical transmission line (the wavelengths of the pumping channels are mutually different).